Yep, Low 80's may be the optimum but these tough girls grow in Southern Mexico, Afganistan and many other inferno countries where they get 125 degree heat. Tons of Love is the Key!..First time back in 2 years. SOoooo. Yea, i grew in an attic. No air conditioning. It was about 87 at the coolest, and about 108 at the hottest. The plant came out AMAZING. Gave it TONS of love though. Really did take a lot of effort.